JP7357503B2 - Writing quality improvement sheet - Google Patents

Description

The present invention relates to a writing quality improving sheet that can improve the writing quality with a touch pen on a touch panel or the like.

2. Description of the Related Art In recent years, image display devices (touch panels) with a position detection function, which serve as both a display device and an input means, have been widely used in various electronic devices. In addition to the types of touch panels that allow input using fingers, there are also types that allow input using touch pens, and touch pens allow for finer and more accurate input operations than with fingers. However, the display module of a touch panel is usually hard. Therefore, the feeling of writing with a touch pen is different from the feeling of writing on paper with a writing instrument, and it is difficult to say that it is good.

In order to solve the problem of writing quality with touch pens on touch panels, consideration has been given to attaching a sheet that improves the writing quality (hereinafter sometimes referred to as a "writing quality improvement sheet") to the top surface of the touch panel. There is. For example, Patent Documents 1 and 2 disclose writing quality improvement sheets in which the coefficient of friction when writing on the surface of the film with a touch pen is adjusted to be within a predetermined range. In particular, Cited Document 1 discloses that the relationship between the static friction coefficient and the dynamic friction coefficient when the touch pen is moved at a speed of 5 cm/sec is defined. Further, Cited Document 2 discloses that the relationship between the static friction coefficient and the dynamic friction coefficient when the touch pen is moved at a speed of 100 mm/sec is defined.

Patent No. 6156647 Patent No. 5774954

However, in the inventions disclosed in Patent Document 1 and Patent Document 2, it was not possible to obtain a sufficient writing feel when writing on paper with a writing instrument (particularly a ballpoint pen). Therefore, there has been a need to develop a sheet for improving the writing quality that even better reproduces the writing quality when writing on paper with a writing instrument.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a writing quality improving sheet that can satisfactorily reproduce the writing quality when written on paper with a writing instrument.

In order to achieve the above object, the present invention first provides a writing quality improvement sheet having a touch pen contacting surface that a touch pen comes into contact with, wherein a touch pen having a pen tip with a diameter of 0.5 mm is attached to the touch pen contacting surface. After bringing the pen tip into contact, a load of 200 g is applied to the touch pen, and while maintaining an angle of 45° between the touch pen and the touch pen contact surface, the touch pen is moved linearly to a predetermined position. Regarding the dynamic friction coefficient measured when sliding at a sliding speed, the dynamic friction coefficient when the sliding speed is 1.5 mm/s is 0.13 or more and 0.35 or less, and the sliding speed is 1.5 mm/s. When the sliding speed is 20 mm/s, the kinetic friction coefficient is 0.15 or more and 0.40 or less, and when the sliding speed is 50 mm/s, the kinetic friction coefficient is 0.18 or more and 0.45 or less. Provided is a sheet for improving writing feel, characterized in that the coefficient of dynamic friction is 0.18 or more and 0.47 or less when the sliding speed is 80 mm/s (Invention 1).

The writing quality improving sheet according to the invention (invention 1) has a coefficient of kinetic friction measured at the four sliding speeds described above, which falls within the ranges described above, so that it can be applied to writing instruments (especially paper) at various writing speeds. It is possible to satisfactorily reproduce the feeling of vibration of paper when writing with a ballpoint pen), thereby making it possible to satisfactorily reproduce the feeling of writing when writing on paper with a writing instrument.

Second, the present invention is a writing quality improving sheet having a touch pen contacting surface that a touch pen comes into contact with, wherein after the tip of a touch pen having a pen tip of 0.5 mm in diameter is brought into contact with the touch pen contacting surface. , when applying a load of 200 g to the touch pen and sliding the touch pen linearly at a predetermined sliding speed while maintaining an angle of 45° between the touch pen and the touch pen contact surface. Regarding the coefficient of kinetic friction measured in .5 mm/sec and the sliding speed is 50 mm/sec, the slope of the line segment is more than 0.0006 and less than 0.0072. (Invention 2).

The writing quality improving sheet according to the invention (invention 2) has the above-mentioned inclination within the above range, so that the vibration feeling of the paper when writing with a writing instrument (particularly a ballpoint pen) on paper at various writing speeds can be improved. This makes it possible to satisfactorily reproduce the feeling of writing on paper with a writing instrument.

Thirdly, the present invention is a writing quality improving sheet having a touch pen contacting surface that a touch pen comes into contact with, wherein after the tip of a touch pen having a pen tip with a diameter of 0.5 mm is brought into contact with the touch pen contacting surface. , when applying a load of 200 g to the touch pen and sliding the touch pen linearly at a predetermined sliding speed while maintaining an angle of 45° between the touch pen and the touch pen contact surface. Regarding the coefficient of kinetic friction measured in In this case, coordinates where the sliding speed is 1.5 mm/s, coordinates where the sliding speed is 20 mm/s, coordinates where the sliding speed is 50 mm/s, and coordinates where the sliding speed is 80 mm/s. The approximate curve obtained by polynomial approximation for the coordinates of four points at a certain coordinate is expressed by the following equations (1) to (4).
Y=aX ² +bX+c...(1)
-5×10 ^-5 ≦a≦-5×10 ^-6 ...(2)
0.0001≦b≦0.008…(3)
0.11≦c≦0.31…(4)
To provide a writing quality improving sheet that satisfies the following (invention 3).

The writing quality improving sheet according to the above invention (invention 3) exhibits the above-mentioned approximate curve, thereby satisfactorily reproducing the vibration sensation of paper when writing with a writing instrument (particularly a ballpoint pen) on paper at various writing speeds. This makes it possible to satisfactorily reproduce the feeling of writing on paper with a writing instrument.

The above inventions (Inventions 1 to 3) include a writing quality improving layer and a base material provided on one side of the writing quality improving layer, and a base material provided on one side of the writing quality improving layer opposite to the base material. It is preferable that the surface is the touch pen contact surface (Invention 4).

The writing quality improving sheet according to the present invention can satisfactorily reproduce the writing quality when written on paper with a writing instrument.

Embodiments of the present invention will be described below.
A writing quality improving sheet according to an embodiment of the present invention has a touch pen contact surface that a touch pen comes into contact with. The writing quality improving sheet according to this embodiment may have touch pen contact surfaces on both sides, but normally only one side of the writing quality improving sheet serves as a touch pen contact surface, and the other surface is used as a touch pen contact surface. This will be the surface to be pasted.

1. Physical Properties of Writing Feel-Improving Sheet (1) Coefficient of Dynamic Friction The writing feeling improving sheet according to the present embodiment is produced by bringing the nib of a touch pen having a nib with a diameter of 0.5 mm into contact with the touch pen contacting surface, and then Measured when applying a load of 200 g to the touch pen and sliding the touch pen linearly at a predetermined sliding speed while maintaining the angle between the touch pen and the contact surface of the touch pen at 45°. It is preferable that the following conditions be satisfied regarding the coefficient of dynamic friction. That is, the dynamic friction coefficient when the sliding speed is 1.5 mm/s is 0.13 or more and 0.35 or less, and the dynamic friction coefficient when the sliding speed is 20 mm/s is 0.13 or more and 0.35 or less. 15 or more and 0.40 or less, and the dynamic friction coefficient when the sliding speed is 50 mm/s is 0.18 or more and 0.45 or less, and the sliding speed is 80 mm/s. The coefficient of dynamic friction in this case is preferably 0.18 or more and 0.47 or less.

In studying the writing feel, the present inventor focused on the fact that the writing speed when writing on paper using a writing instrument varies depending on the scribe and the content being written. For example, when taking simple notes, the writing speed tends to be relatively fast, while when learning how to write kanji, the writing speed tends to be relatively slow. Upon further detailed study, the present inventor discovered that the coefficient of kinetic friction when writing on paper with a writing instrument varies depending on the writing speed. For example, when writing on paper with a ballpoint pen, it was found that the slower the writing speed, the smaller the coefficient of kinetic friction, and the faster the writing speed, the larger the coefficient of kinetic friction. It could not be said that conventional writing quality improving sheets sufficiently reproduce such fluctuations in the coefficient of dynamic friction depending on the writing speed.

On the other hand, the writing quality improving sheet according to the present embodiment satisfies the above-mentioned dynamic friction coefficient for each of the four sliding speeds described above, so that a touch pen can be attached to the touch panel to which the writing quality improving sheet is pasted. When using the touch pen, the vibration sensation transmitted to the hand holding the touch pen is very similar to the vibration sensation you get when writing on paper with a writing instrument (particularly a ballpoint pen). In particular, in the writing quality improving sheet according to the present embodiment, fluctuations in the coefficient of dynamic friction depending on the writing speed are well reproduced. As a result, the writing quality improving sheet according to the present embodiment can achieve an unprecedented writing quality.

From the viewpoint of achieving a better writing feel, the coefficient of dynamic friction at a sliding speed of 1.5 mm/s is preferably 0.17 or more, particularly preferably 0.20 or more. . Further, the dynamic friction coefficient is preferably 0.30 or less, particularly preferably 0.29 or less.

Further, from the same viewpoint, the dynamic friction coefficient when the sliding speed is 20 mm/s is preferably 0.20 or more, particularly preferably 0.25 or more. Further, the dynamic friction coefficient is preferably 0.36 or less, particularly preferably 0.33 or less.

Further, from the same viewpoint, the dynamic friction coefficient when the sliding speed is 50 mm/s is preferably 0.25 or more, particularly preferably 0.30 or more. Further, the dynamic friction coefficient is preferably 0.40 or less, particularly preferably 0.37 or less.

Further, from the same viewpoint, the dynamic friction coefficient when the sliding speed is 80 mm/s is preferably 0.25 or more, and particularly preferably 0.30 or more. Further, the dynamic friction coefficient is preferably 0.40 or less, particularly preferably 0.37 or less.

Details of the method for measuring the coefficient of dynamic friction described above are as described in the test examples described later.

(2) Inclination regarding dynamic friction coefficient In the writing quality improvement sheet according to the present embodiment, it is also preferable that the following conditions regarding the “inclination” are satisfied regarding the dynamic friction coefficient measured as described above.

That is, in the writing quality improvement sheet according to the present embodiment, a load of 200 g is applied to the touch pen after the touch pen contacting surface is brought into contact with the tip of the touch pen having a pen tip of 0.5 mm in diameter. At the same time, the above measurement results regarding the coefficient of kinetic friction measured when the touch pen is slid linearly at a predetermined sliding speed while maintaining the angle formed by the touch pen and the touch pen contact surface at 45° is plotted on a coordinate plane with the above sliding speed as the horizontal axis (unit: mm/sec) and the above dynamic friction coefficient as the vertical axis, the coordinates where the above sliding speed is 1.5 mm/sec and the above sliding It is also preferable that the slope of the line segment connecting the coordinate with the moving speed of 50 mm/sec is greater than 0.0006 and less than 0.0072.

Generally, a sliding speed of 1.5 mm/sec corresponds to a writing speed when writing is fairly slow, and a sliding speed of 50 mm/sec corresponds to a writing speed when writing quickly. In the writing quality improving sheet according to the present embodiment, since the above-mentioned inclination is within the above range, the coefficient of dynamic friction increases as the sliding speed increases from low to high. This generally shows the relationship between the writing speed and the coefficient of kinetic friction when writing with a writing instrument on paper (i.e., when writing slowly, the coefficient of kinetic friction decreases, and when writing quickly, the coefficient of kinetic friction increases). This relationship) is well reproduced, making it possible to achieve an unprecedented writing quality.

From the viewpoint of achieving a better writing feel, the above-mentioned slope is preferably 0.0008 or more, more preferably 0.0010 or more, particularly preferably 0.0011 or more, and is preferably 0.0013 or more. Further, from the same viewpoint, the above-mentioned slope is preferably 0.0050 or less, more preferably 0.0030 or less, particularly preferably 0.0026 or less, and even more preferably 0.0020 or less. It is preferable that

Note that when a line segment connecting the coordinates of a sliding speed of 1.5 mm/sec and the coordinates of a sliding speed of 50 mm/sec is expressed by a linear equation, the intercept of the linear equation is preferably 0.10 or more. , particularly preferably 0.16 or more, and more preferably 0.20 or more. Further, the intercept is preferably 0.35 or less, particularly preferably 0.30 or less, and even more preferably 0.28 or less. When the above-mentioned intercept falls within the above-mentioned range, it becomes easier to reproduce the vibration sensation of the writing instrument when writing on paper with the writing instrument.

In addition, from the viewpoint that it is easy to adjust the slope of the line segment connecting the coordinates of the sliding speed of 1.5 mm/sec and the coordinates of the sliding speed of 50 mm/sec to the above-mentioned range, in the coordinate plane obtained as above, The slope of the line segment connecting the coordinates where the sliding speed is 1.5 mm/sec and the coordinates where the sliding speed is 20 mm/sec is preferably 0.0010 or more, particularly 0.0013 or more. is preferable, and more preferably 0.0018 or more. Further, from the same viewpoint, the slope of the line segment connecting the coordinates where the sliding speed is 1.5 mm/sec and the coordinates where the sliding speed is 20 mm/sec is preferably 0.0090 or less, and especially It is preferably 0.0050 or less, more preferably 0.0040 or less.

In addition, from the viewpoint of easily adjusting the slope of the line segment connecting the coordinates of the sliding speed of 1.5 mm/sec and the coordinates of the sliding speed of 50 mm/sec to the above-mentioned range, in the coordinate plane obtained as above, The slope of the line segment connecting the coordinates where the sliding speed is 1.5 mm/sec and the coordinates where the sliding speed is 80 mm/sec is preferably 0.0005 or more, particularly 0.0007 or more. is preferable, and more preferably 0.0009 or more. Further, from the same viewpoint, the slope of the line segment connecting the coordinates where the sliding speed is 1.5 mm/sec and the coordinates where the sliding speed is 80 mm/sec is preferably 0.0030 or less, and particularly It is preferably 0.0020 or less, more preferably 0.0015 or less.

(3) Approximate curve regarding dynamic friction coefficient In the writing quality improvement sheet according to the present embodiment, it is also preferable that the following conditions regarding the “approximate curve” are satisfied regarding the dynamic friction coefficient measured as described above.

That is, in the writing quality improvement sheet according to the present embodiment, a load of 200 g is applied to the touch pen after the touch pen contacting surface is brought into contact with the tip of the touch pen having a pen tip of 0.5 mm in diameter. At the same time, the above measurement results regarding the coefficient of kinetic friction measured when the touch pen is slid linearly at a predetermined sliding speed while maintaining the angle formed by the touch pen and the touch pen contact surface at 45° When is plotted on a coordinate plane with the above sliding speed as the horizontal axis (X axis) (unit: mm/sec) and the above dynamic friction coefficient as the vertical axis (Y axis), the above sliding speed is 1.5 mm/sec. Polynomial approximation is applied to the coordinates of four points: the coordinate where the sliding speed is s, the coordinate where the sliding speed is 20 mm/s, the coordinate where the sliding speed is 50 mm/s, and the coordinate where the sliding speed is 80 mm/s. The approximate curve obtained by using the following equations (1) to (4)
Y=aX ² +bX+c...(1)
-5×10 ^-5 ≦a≦-5×10 ^-6 ...(2)
0.0001≦b≦0.008…(3)
0.11≦c≦0.31…(4)
It is also preferable to satisfy the following.

In the writing quality improvement sheet according to the present embodiment, by forming the above-mentioned approximate curve, the fluctuation of the coefficient of dynamic friction with respect to the fluctuation of the sliding speed tends to match that when writing on paper using a writing instrument. As a result, the relationship between the writing speed and the coefficient of dynamic friction when writing on paper using a writing instrument can be well reproduced, making it possible to achieve an unprecedented writing feel.

From this point of view, the value of a in the above formula (2) is preferably −4×10 ⁻⁵ or more, particularly preferably −3×10 ⁻⁵ or more. Further, the value of a in the above formula (2) is preferably −8×10 ⁻⁶ or less, particularly preferably −1×10 ⁻⁵ or less.

Further, from the same viewpoint, the value of b in the above formula (3) is preferably 0.0010 or more, particularly preferably 0.0020 or more. Further, the value of b in the above formula (3) is preferably 0.0050 or less, particularly preferably 0.0035 or less.

Further, from the same viewpoint, the value of c in the above formula (4) is preferably 0.16 or more, and particularly preferably 0.20 or more. Further, the value of c in the above formula (4) is preferably 0.29 or less, particularly preferably 0.28 or less.

(4) Optical properties The haze value of the writing quality improving sheet according to this embodiment is not particularly limited, and is preferably 0.1% or more, more preferably 0.5% or more, but has a sufficient haze value. From the viewpoint of obtaining anti-glare properties, it is particularly preferable that the content is 10% or more. On the other hand, the haze value is preferably 95% or less, particularly preferably 50% or less, and even more preferably 20% or less. When the haze value is 95% or less, the writing quality improving sheet according to the present embodiment has higher transparency. Note that the haze value described above was measured according to JIS K7136:2000, and the detailed measurement method is as described in the test example described below.

The writing quality improving sheet according to the present embodiment preferably has a total light transmittance of 70% or more, particularly preferably 80% or more, and more preferably 88% or more. When the total light transmittance is 70% or more, the writing quality improving sheet according to the present embodiment has higher transparency. On the other hand, the upper limit of the total light transmittance is not particularly limited, and is preferably, for example, 100% or less, particularly preferably 96% or less, and even more preferably 92% or less. The above-mentioned total light transmittance was measured according to JIS K7361-1:1997, and the detailed measurement method is as described in the test example described below.

(5) Scratch Resistance The writing quality improvement sheet according to this embodiment has scratches that occur when the touch pen contacting surface is rubbed 10 times back and forth for 10 times using #0000 steel wool under a load of 250 g/ ^cm2 . The number is preferably 10 or less, particularly preferably 5 or less, and even more preferably 0. As a result, the touch pen contacting surface of the writing quality improving sheet according to the present embodiment can exhibit good hard coating properties and has excellent scratch resistance. Incidentally, such scratch resistance based on steel wool hardness evaluation can be easily achieved when the writing quality improving sheet according to the present embodiment includes a hard coat layer as the writing quality improving layer, as will be described later. . Further, the detailed method for measuring the scratch resistance is as described in the test examples described below.

2. Layer structure of the writing feeling improving sheet The layer structure of the writing feeling improving sheet according to this embodiment satisfies the coefficient of dynamic friction for each sliding speed described above for the touch pen contact surface, and is applicable to a touch panel on which the touch pen is used. There is no particular limitation as long as.

From the viewpoint that it is easy to achieve the above-mentioned dynamic friction coefficient for each sliding speed and to easily adjust other physical properties, the writing taste improving sheet according to the present embodiment has a writing taste improving layer and a writing taste improving layer. It is preferable to include a base material provided on one surface side. When having this layer structure, it is preferable that the surface of the writing quality improving layer opposite to the base material is the touch pen contacting surface.

(1) Base material The above-mentioned base material can be appropriately selected from materials suitable for touch panels in which touch pens are used. For example, as the base material, a plastic film, a glass plate, etc. can be used, but it is preferable to use a plastic film from the viewpoint of good affinity with the writing quality improving layer.

Examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films such as polyethylene film and polypropylene film, cellophane, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, Polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, Etherimide film, fluororesin film, polyamide film, acrylic resin film, polyurethane resin film, norbornene polymer film, cyclic olefin polymer film, cyclic conjugated diene polymer film, vinyl alicyclic hydrocarbon polymer film, etc. plastic films or laminated films thereof. Among these, from the viewpoint of easily obtaining desired optical properties, it is preferable to use a polyester film, and it is particularly preferable to use polyethylene terephthalate.

In addition, the above-mentioned base material may be coated with a primer or the like on one or both sides, if desired, for the purpose of improving adhesion with layers provided on the surface (writing quality improving layer, adhesive layer described below, etc.). It may be provided with an easy-adhesion layer, a surface treatment layer by an oxidation method, a roughening method, or the like. Examples of the above oxidation methods include corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone/ultraviolet treatment, and the like. Moreover, examples of the above-mentioned unevenening method include a sandblasting method, a solvent treatment method, and the like.

In addition, in this specification, the easily adhesive layer and the surface treatment layer mentioned above shall be defined as a part which comprises a base material. Therefore, for example, even if a writing quality improving sheet is assumed in which a writing quality improving layer is directly laminated on a base material, the base material of such a writing quality improving sheet does not include the above-mentioned easy-adhesion layer or the writing quality improving sheet. The possibility of the presence of a surface treatment layer is not excluded.

The thickness of the base material is preferably 20 μm or more, more preferably 80 μm or more, particularly preferably 100 μm or more, and even more preferably 120 μm or more. By having the lower limit of the thickness of the base material within the above range, it becomes easier to exhibit sufficient pencil hardness, and when various layers (for example, an adhesive layer) are provided on the side of the base material opposite to the writing quality improving layer. Even so, such a layer makes it difficult for the writing quality of the writing quality improving layer to be affected. Further, the thickness of the base material is preferably 300 μm or less, more preferably 200 μm or less, and particularly preferably 150 μm or less. When the upper limit of the thickness of the base material is within the above range, the writing quality improving sheet according to the present embodiment has appropriate flexibility and is easy to handle.

(2) Writing quality improving layer The material for forming the writing quality improving layer is not particularly limited as long as it can achieve the above-mentioned dynamic friction coefficient for each sliding speed. Further, the writing quality improving layer may be a hard coat layer having hard coat properties, and in this case, the touch pen contacting surface tends to have good scratch resistance.

The writing quality improving layer is preferably formed by curing the coating composition described below. In particular, the coating composition preferably contains a curable component and a surface conditioner.

(2-1) Curable Component The curable component is a component that is cured by a trigger such as active energy rays or heat, and includes, for example, an active energy ray curable component, a thermosetting component, and the like. In this embodiment, it is preferable to use an active energy ray-curable component from the viewpoint of the hardness of the writing quality improving layer to be formed and the heat resistance of the base material (plastic film).

The active energy ray-curable component is preferably one that can be cured by irradiation with active energy rays to exhibit a predetermined hardness and achieve the above-mentioned physical properties.

Specific active energy ray-curable components include polyfunctional (meth)acrylate monomers, (meth)acrylate prepolymers, and active energy ray-curable polymers, among which polyfunctional (meth)acrylate It is preferable that the polymer is a monomer based on the monomer and/or a prepolymer based on the (meth)acrylate. The polyfunctional (meth)acrylate monomer and the (meth)acrylate prepolymer may be used alone or in combination. In addition, in this specification, (meth)acrylate means both acrylate and methacrylate. The same applies to other similar terms.

Examples of polyfunctional (meth)acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate. (meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, allylated Cyclohexyl di(meth)acrylate, Isocyanurate di(meth)acrylate, Trimethylolpropane tri(meth)acrylate, Dipentaerythritol tri(meth)acrylate, Propionic acid modified dipentaerythritol tri(meth)acrylate, Pentaerythritol tri(meth)acrylate ) acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, pentaerythritol tetra(meth)acrylate, propionic acid modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate ) acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and other polyfunctional (meth)acrylates. These may be used alone or in combination of two or more.

On the other hand, examples of (meth)acrylate-based prepolymers include urethane acrylate-based, polyester acrylate-based, epoxy acrylate-based, and polyol acrylate-based prepolymers. Among these, it is preferable to use a urethane acrylate prepolymer from the viewpoint that it is easy to achieve the dynamic friction coefficient for each sliding speed described above.

As the urethane acrylate prepolymer, for example, a reaction product obtained by esterifying the hydroxyl group of a polyurethane preoligomer obtained from a polyether polyol or a polyester polyol and a polyisocyanate with (meth)acrylic acid; a polyether polyol Alternatively, there may be mentioned a reaction product obtained by reacting a terminal isocyanate polyurethane oligomer obtained by reacting a polyester polyol with a polyisocyanate and a hydroxyl group-containing (meth)acrylic acid.

(2-2) Surface Conditioning Agent When the coating composition contains a surface conditioning agent, the occurrence of streak-like defects, unevenness, etc. is suppressed in the writing quality improving layer that is formed. As a result, the film thickness becomes uniform, and the writing quality improving sheet exhibits a more excellent appearance, and also tends to have desired optical properties (haze value, total light transmittance, etc.). In addition, since the surface conditioner is likely to be exposed on the surface of the writing quality improving layer of the writing quality improving sheet, the slipperiness of the writing quality improving layer can be adjusted, making it easier to achieve the above-mentioned coefficient of dynamic friction for each sliding speed. Become.

Examples of the surface conditioning agent include fluorine-based, silicone-based, acrylic-based, vinyl-based, etc. Preferably, at least one surface conditioner is used. In addition, one type of surface conditioner may be used alone, or two or more types may be used in combination.

As the fluorine-based surface conditioner, compounds having a perfluoroalkyl group or a fluorinated alkenyl group in the main chain or side chain can be preferably mentioned. Preferred commercially available products include BYK-340 manufactured by BYK Chemie Japan, Ftergent 650A manufactured by Neos, Megafac RS-75 manufactured by DIC, and V-8FM manufactured by Osaka Organic Chemical Industry Co., Ltd. However, it is not limited to these. The silicone-based surface conditioner is preferably polydimethylsiloxane or modified polydimethylsiloxane, and particularly preferably polydimethylsiloxane.

The content of the surface conditioner in the coating composition is preferably 0.01 part by mass or more, particularly preferably 0.1 part by mass or more, based on 100 parts by mass of the curable component. The amount is preferably 0.2 parts by mass or more. The content of the surface conditioner in the coating composition is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, particularly 3 parts by mass, based on 100 parts by mass of the curable component. It is preferably at most 1 part by mass, more preferably at most 1 part by mass. When the content of the surface conditioner is within the above range, the appearance of the writing quality improving sheet can be effectively improved. Further, the optical properties (haze value, total light transmittance, etc.) are likely to be adjusted within the above range. Furthermore, the writing quality improving layer can easily achieve the above-mentioned dynamic friction coefficient for each sliding speed.

(2-3) Fine particles When the coating composition contains fine particles, the surface of the writing quality improving layer formed becomes appropriately rough, making it easier to adjust the haze value and exhibiting the desired anti-glare properties. becomes easier.

Note that the above-mentioned fine particles refer to those having a larger average particle size than the silica nanoparticles described below. For example, the average particle diameter of the fine particles is preferably 1 μm or more, particularly preferably 2 μm or more, and even more preferably 3 μm or more. Further, the average particle diameter of the fine particles is preferably 20 μm or less, particularly preferably 14 μm or less, and even more preferably 8 μm or less. When the average particle diameter of the fine particles is within the above range, it becomes easier to adjust the haze value.

Further, the particle size variation coefficient (CV value) of the fine particles expressed by the following formula is preferably 3% or more, particularly preferably 8% or more. Further, the coefficient of variation (CV value) of the particle size is preferably 70% or less, particularly preferably 45% or less, and even more preferably 25% or less. When the CV value of the fine particles is within the above range, it becomes easier to adjust the uneven shape of the surface, it becomes easier to achieve the above-mentioned dynamic friction coefficient for each sliding speed, and it becomes easier to adjust the haze value. .
Particle size variation coefficient (CV value) = (standard deviation particle size/average particle size) x 100

The average particle diameter and particle diameter coefficient of variation (CV value) of the fine particles mentioned above were determined using a laser diffraction scattering particle size distribution analyzer using a 5% by mass dispersion prepared using methyl ethyl ketone as a dispersion medium as a sample. Use a few drops and take the measured value.

The above-mentioned fine particles may be organic fine particles, inorganic fine particles, or resin fine particles having both inorganic and organic properties. From the viewpoint of easy adjustment of haze value, organic fine particles or resin fine particles having both inorganic and organic properties are preferred.

Examples of organic particles include acrylic resin particles (for example, polymethyl methacrylate particles), silicone particles, melamine resin particles, acrylic-styrene copolymer particles, polycarbonate particles, polyethylene particles, and polystyrene particles. Examples include benzoguanamine-based resin particles and benzoguanamine-based resin particles. These resins may also be crosslinked. Among the above, acrylic resin fine particles and silicone fine particles are preferred from the viewpoint of making it easier to adjust the haze value.

Examples of the inorganic fine particles include fine particles made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like.

As the resin fine particles having both inorganic and organic properties, silicone fine particles (for example, Tospar series manufactured by Momentive Performance Materials Japan) are particularly preferred.

In addition, the above-mentioned fine particles may be used alone or in combination of two or more types.

The fine particles may have undergone desired surface modification. Further, the shape of the fine particles may be a fixed shape such as a sphere, or may be an unspecified shape, but this makes it easier to achieve the coefficient of kinetic friction for each sliding speed as described above, and to further reduce the haze value. From the viewpoint of easy adjustment, a regular shape is preferred, and a spherical shape is particularly preferred.

The content of fine particles in the coating composition is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, particularly 1 part by mass, based on 100 parts by mass of the curable component. It is preferably at least 3 parts by mass, and more preferably at least 3 parts by mass. Further, the content of fine particles in the coating composition is preferably 50 parts by mass or less, particularly preferably 30 parts by mass or less, and more preferably 10 parts by mass or less, based on 100 parts by mass of the curable component. It is preferable that When the content of fine particles is within the above range, it becomes easy to achieve the above-mentioned dynamic friction coefficient for each sliding speed while exhibiting anti-glare properties.

(2-4) Other components The coating composition in this embodiment may contain various additives in addition to the above components. Examples of various additives include photopolymerization initiators, silica nanoparticles, ultraviolet absorbers, antioxidants, light stabilizers, antistatic agents, silane coupling agents, antiaging agents, thermal polymerization inhibitors, colorants, and interfaces. Examples include activators, storage stabilizers, plasticizers, lubricants, antifoaming agents, organic fillers, wettability improvers, coating surface improvers, and the like.

Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]- 2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2- Methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl Examples include dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, and the like. These may be used alone or in combination of two or more.

The content of the photopolymerization initiator in the coating composition is preferably 1 part by mass or more, particularly preferably 2 parts by mass or more, based on 100 parts by mass of the curable component. Further, the content of the photopolymerization initiator in the coating composition is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, based on 100 parts by mass of the curable component.

(2-5) Thickness The thickness of the writing quality improving layer is preferably 0.1 μm or more, particularly preferably 1 μm or more, and even more preferably 2 μm or more. Further, the thickness of the writing quality improving layer is preferably 30 μm or less, more preferably 20 μm or less, and particularly preferably 10 μm or less. When the thickness of the writing quality improving layer is within the above range, the writing quality improving sheet according to the present embodiment can easily achieve the dynamic friction coefficient for each sliding speed described above.

(3) Other members The writing quality improving sheet according to this embodiment may further include other layers as long as the writing quality improving layer is on the outermost surface. For example, an adhesive layer may be formed on the surface of the base material opposite to the writing quality improving layer, or a release sheet may be laminated on the adhesive layer.

As the adhesive constituting the adhesive layer, those commonly used for optical purposes can be used, such as acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, and polyester adhesives. Examples include adhesives, polyvinyl ether adhesives, and the like. Among these, acrylic pressure-sensitive adhesives that exhibit desired adhesiveness and have excellent optical properties and durability are preferred.

The thickness of the adhesive layer is preferably 5 μm or more, particularly preferably 10 μm or more, and even more preferably 20 μm or more. Further, the thickness of the adhesive layer is preferably 300 μm or less, more preferably 100 μm or less, and particularly preferably 50 μm or less.

Examples of release sheets include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, Polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, A liquid crystal polymer film or the like is used. Moreover, these crosslinked films are also used. Furthermore, a laminated film of these may be used.

It is preferable that the release surface (the surface in contact with the adhesive layer) of the release sheet is subjected to a release treatment. Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

The thickness of the release sheet is not particularly limited, but is usually about 20 to 150 μm.

3. Method for manufacturing the writing quality improving sheet The method for manufacturing the writing quality improving sheet according to the present embodiment is not particularly limited as long as the writing quality improving sheet can achieve the coefficient of dynamic friction for each sliding speed described above. For example, the writing quality improving sheet can be manufactured by applying a coating liquid containing the above-mentioned coating composition and optionally a solvent to a base material and curing it to form a writing quality improving layer. preferable.

Solvents can be used to improve coating properties, adjust viscosity, adjust solid content concentration, etc., and can be used without particular limitations as long as they dissolve curable components and disperse fine particles. .

Specific examples of solvents include alcohols such as methanol, ethanol, isopropanol, butanol, and octanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and esters such as ethyl acetate, butyl acetate, ethyl lactate, and γ-butyrolactone. Ethers such as ethylene glycol monomethyl ether (methyl cellosolove), ethylene glycol monoethyl ether (ethyl cellosolove), diethylene glycol monobutyl ether (butyl cellosolove), propylene glycol monomethyl ether; aromatic hydrocarbons such as benzene, toluene, xylene; dimethylformamide , dimethylacetamide, N-methylpyrrolidone, and other amides.

The coating solution of the coating composition may be applied by a conventional method, such as a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, or a gravure coating method. After applying the coating solution of the coating composition, it is preferable to dry the coating film at 40 to 120°C for about 30 seconds to 5 minutes.

When the coating composition has active energy ray curability, the coating composition is cured by irradiating the coating film of the coating composition with active energy rays such as ultraviolet rays and electron beams. The ultraviolet irradiation can be performed using a high-pressure mercury lamp, Fusion H lamp, xenon lamp, etc., and the amount of ultraviolet irradiation is preferably about 50 to 1000 mW/cm ² , an amount of 50 to 1000 mJ/cm ² , and an intensity of 100 to 500 mW. /cm ² and a light amount of about 100 to 500 mJ/cm ² is particularly preferable. On the other hand, electron beam irradiation can be performed using an electron beam accelerator or the like, and the amount of electron beam irradiation is preferably about 10 to 1000 krad.

4. Use of writing quality improving sheet The writing quality improving sheet according to this embodiment can be used as a sheet constituting the outermost layer of a touch panel (image display device with position detection function) on which a touch pen is used. Specifically, it is used by being laminated on a cover material of a display module such as a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, or a touch panel having a touch sensor. is preferred. The writing quality improving sheet is preferably laminated onto the cover material by pasting it through the adhesive layer described above.

Note that the touch pen used for the writing quality improvement sheet according to the present embodiment is not particularly limited, and any conventionally known touch pen can be used. For example, as the touch pen, one having a nib made of polyacetal, one having a nib made of hard felt, one having a nib made of elastomer, etc. can be used. Among these, it is preferable to use a touch pen having an elastomer nib from the viewpoint of easily satisfying the dynamic friction coefficient for each sliding speed described above.

Further, the shape of the pen tip of the touch pen used for the writing quality improvement sheet according to the present embodiment is not particularly limited, and may be appropriately selected from disc-shaped, circular, polygonal, etc. However, from the viewpoint of being able to feel the vibration when writing with a ballpoint pen, a circular shape is preferable. When the shape of the pen tip of the touch pen is circular, the diameter of the pen tip is preferably 0.1 mm or more, particularly preferably 0.2 mm or more, and more preferably 0.3 mm or more. . Further, the diameter is preferably 5 mm or less, particularly preferably 2 mm or less, and further preferably 1 mm or less.

By satisfying the above-mentioned dynamic friction coefficient for each sliding speed, the writing quality improving sheet according to the present embodiment can satisfactorily reproduce the vibration feeling of a paper writing instrument (particularly a ballpoint pen) when writing on paper with a writing instrument (especially a ballpoint pen). . As a result, the feeling of writing on paper with a writing instrument is well reproduced.

5. Another Embodiment The writing quality improving sheet according to the present embodiment described above may constitute another embodiment of the present invention together with other elements.

For example, another embodiment of the present invention may be a set of the above-described writing quality improvement sheet and a touch pen used with the writing quality improvement sheet. Examples of touch pens in this set include those with polyacetal nibs, hard felt nibs, and elastomer nibs. From the viewpoint of easy realization, it is preferable to use a touch pen having an elastomer nib.

Further, another embodiment of the present invention may be an image display device (particularly a touch panel) including the above-mentioned writing quality improving sheet on the outermost surface.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

For example, another layer may be interposed between the base material and the writing quality improving layer in the writing quality improving sheet according to this embodiment.

Hereinafter, the present invention will be explained in more detail with reference to examples, but the scope of the present invention is not limited to these examples.

[Preparation example]
The materials listed in Table 1 were mixed in the compositions shown in Table 2 to obtain coating compositions C1 to C7. The blending ratios shown in Table 2 are based on solid content equivalent values. Furthermore, each of the obtained coating compositions was diluted with propylene glycol monomethyl ether to obtain coating liquids of coating compositions C1 to C7.

[Example 1]
(1) Formation of writing quality improving layer A Mayer bar was used on one side of a polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc., product name: "Lumirror U48", thickness 125 μm), which has an easily adhesive layer on both sides as a base material. After applying the coating solution of coating composition C1 obtained in the above-mentioned preparation example to form a coating film, the coating film was dried by heating at 70 ° C. for 1 minute using an oven. Ta.

Next, in a nitrogen atmosphere, the coating film was cured by irradiating ultraviolet rays under the following conditions using an ultraviolet irradiation device (manufactured by GS Yuasa Corporation, product name: "Nitrogen purge small conveyor type UV irradiation device CSN2-40"). A writing quality improving layer having a thickness of 10 μm was formed.
[Ultraviolet irradiation conditions]
・Light source: High pressure mercury lamp ・Lamp power: 1.4kW
・Conveyor speed: 1.2m/min
・Illuminance: 100mW/ ^cm2
・Light intensity: 240mJ/ ^cm2
・Oxygen concentration: 1% or less

(2) Formation of adhesive layer 95 parts by mass of n-butyl acrylate and 5 parts by mass of acrylic acid were copolymerized by a solution polymerization method to prepare a (meth)acrylic acid ester copolymer. When the molecular weight of this (meth)acrylic acid ester copolymer was measured by the method described below, the weight average molecular weight (Mw) was 1.5 million.

99.8 parts by mass of the obtained (meth)acrylic acid ester copolymer (in terms of solid content; the same applies hereinafter) and 0.0 parts by mass of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane as a crosslinking agent. 2 parts by mass, sufficiently stirred, and diluted with toluene to obtain a coating liquid of the adhesive composition.

Next, an applicator was used to apply the release sheet to the release surface of a release sheet (manufactured by Lintec, product name: "SP-PET381031"), which was made by forming a silicone release agent layer on one side of a 38 μm thick polyethylene terephthalate film. A coating film was formed by applying the coating solution of the adhesive composition obtained as described above. Furthermore, the coating film was dried by heating at 100°C for 3 minutes using an oven, and by curing for 7 days at 23°C and 50% RH, a 25 μm thick adhesive was applied on the release sheet. formed a layer.

Here, the weight average molecular weight (Mw) mentioned above is the weight average molecular weight in terms of polystyrene measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).
<Measurement conditions>
・GPC measurement device: Tosoh Corporation, HLC-8320
・GPC column (passed in the following order): TSK gel superH-H manufactured by Tosoh Corporation
TSK gel superHM-H
TSK gel superH2000
・Measurement solvent: Tetrahydrofuran ・Measurement temperature: 40℃

(3) Formation of writing quality improving sheet The surface on the base material side of the laminate of the base material and writing quality improving layer obtained in step (1) described above, and the surface on the base material side of the laminate obtained in step (2) described above. By laminating the surfaces of the laminate of the release sheet and the adhesive layer on the adhesive layer side, the writing quality improving layer, the base material, the adhesive layer, and the release sheet are laminated in this order to improve the writing quality. Got a sheet.

[Examples 2-5, Comparative Examples 1-2]
A writing quality improving sheet was prepared in the same manner as in Example 1, except that the type of coating composition used and the thickness of the writing quality improving layer were changed as shown in Table 3.

[Test Example 1] (Measurement of optical properties)
The release sheet was peeled off from the writing quality improving sheets produced in Examples and Comparative Examples, and the exposed surface (adhesive surface) of the exposed adhesive layer was bonded to a glass plate (thickness: 1.2 mm). was used as the sample for measurement.

After background measurement was performed on the glass plate alone, the measurement sample was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH-5000") in accordance with JIS K7136:2000. The haze value (%) of the writing quality improving sheet was measured, and the total light transmittance (%) of the writing quality improving sheet was measured according to JIS Z 8741:1997. These results are shown in Table 3.

[Test Example 2] (Measurement of pencil hardness)
The release sheet was peeled off from the writing quality improving sheets produced in Examples and Comparative Examples, and the exposed surface (adhesive surface) of the exposed adhesive layer was bonded to a glass plate (thickness: 1.2 mm). was used as the sample for measurement.

The writing quality improvement layer side (touch pen contact surface) of the above measurement sample was tested using a pencil scratch coating hardness tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name "NP") according to JIS K5600-5-4. The scratch hardness was measured by the pencil method under the conditions of a load of 750 g and a speed of 1.0 mm/s in accordance with 1999. The results are shown in Table 3.

[Test Example 3] (Evaluation of scratch resistance)
The release sheet was peeled off from the writing quality improving sheets produced in Examples and Comparative Examples, and the exposed surface (adhesive surface) of the exposed adhesive layer was bonded to a glass plate (thickness: 1.2 mm). was used as the sample for measurement.

The surface of the writing quality improvement layer side (touch pen contact surface) of the measurement sample was rubbed 10 times back and forth for 10 cm at a load of 125 g/cm ² using #0000 steel wool. The surface of the writing quality improving layer was visually confirmed under a three-wavelength fluorescent lamp, and the scratch resistance was evaluated based on the following criteria. The results are shown in Table 3.
A: No scratches were observed.
B: 10 or less scratches were observed.
C: Eleven or more scratches were confirmed.

[Test Example 3] (Friction measurement)
The release sheet was peeled off from the writing quality improving sheets produced in Examples and Comparative Examples, and the exposed surface (adhesive surface) of the exposed adhesive layer was bonded to a glass plate (thickness: 1.2 mm). was used as the sample for measurement.

The above sample for measurement was placed on the measuring cart of a static friction measuring machine (manufactured by Trinity Lab, product name: "Tribomaster TL201Ts") so that the surface on the side of the writing quality improvement layer (the touch pen contact surface) was facing upward. . The measuring trolley is configured to reciprocate in a predetermined direction while keeping the surface on which the measuring sample is placed horizontally as the static friction measuring device is used.

Subsequently, the touch pen (test touch pen) was fixed to the static dynamic friction measuring device so that the pen tip was in contact with the touch pen contact surface. At this time, the touch pen was tilted and fixed so that the angle between the touch pen and the contact surface of the touch pen was 45°. Moreover, the direction of inclination at that time was such that it was inclined toward the traveling direction of the measuring trolley and parallel to the traveling direction. As the touch pen, a touch pen having an elastomer nib (manufactured by Wacom, product name "ACK-20004", nib diameter: 0.5 mm) was used.

Next, with a load of 200 g applied to the touch pen, the above-mentioned measuring cart was moved at four speeds: 1.5 mm/s, 20 mm/s, 50 mm/s, and 80 mm/s. By moving the touch pen at (sliding speed), the touch pen was slid on the touch pen contact surface (sliding distance: 100 mm), and the coefficient of dynamic friction was calculated for each sliding speed based on the friction force measured at that time. . The results are shown in Table 3.

Further, as a reference, the coefficient of dynamic friction when writing on paper with a writing instrument was also measured in the same manner as above. Specifically, 20 sheets of commercially available paper (manufactured by KOKUYO Co., Ltd., product name ``Campus Loose Leaf - Easy to Write'', product model number ``No-S836BT'', size: B5, ruled width: B ruled) were stacked together, and the above After installing the writing instrument on the measuring trolley of the static-dynamic friction measuring machine, the writing instrument was fixed to the static-dynamic friction measuring machine so that the pen tip was in contact with the outermost surface of the stacked papers. Here, the writing instruments used are ballpoint pen A (manufactured by BIC, product name "Orange EG 0.7", oil-based ballpoint pen, diameter of the pen tip: 0.7 mm), ballpoint pen B (manufactured by BIC, product name "Orange EG 1"). 0'', oil-based ballpoint pen, nib diameter: 1.0 mm) and a pencil (manufactured by Mitsubishi Pencil Co., product name: ``Mitsubishi Pencil Uni B'', lead hardness: B). Then, the writing instrument was slid on the surface of the paper at the four sliding speeds described above, and the coefficient of dynamic friction was calculated based on the frictional force measured at that time. The results are also shown in Table 3.

Furthermore, the coefficients of dynamic friction for each of the four sliding speeds for the Examples, Comparative Examples, and Reference Examples obtained as described above are calculated using the sliding speed as the horizontal axis (X axis) (unit: mm/sec). , plotted on a coordinate plane with the coefficient of dynamic friction as the vertical axis (Y-axis).

In the above coordinate plane, the slope of the line segment connecting the coordinates where the sliding speed is 1.5 mm/sec and the coordinates where the sliding speed is 20 mm/sec (related to "20 mm/sec" in Table 3) The inclination of the line segment connecting the coordinates where the sliding speed is 1.5 mm/sec and the coordinates where the sliding speed is 50 mm/sec (inclination related to "vs. 50 mm/sec" in Table 3) Connect the coordinates where the sliding speed is 1.5 mm/s and the coordinates where the sliding speed is 80 mm/s. The slope of the line segment (expressed as the slope relative to "80 mm/sec" in Table 3) was calculated. The results are also shown in Table 3.

Further, in the above coordinate plane, polynomial approximation was performed for the coordinates of four points whose sliding speeds were 1.5 mm/s, 20 mm/s, 50 mm/s, and 0 mm/s, and an equation of an approximate curve was obtained. Then, convert the formula into the following formula (1)
Y=aX ² +bX+c...(1)
Table 3 shows the values of coefficients a, b, and c in the case expressed as .

[Test Example 4] (Evaluation of writing quality)
The release sheet was peeled off from the writing quality improving sheets produced in Examples and Comparative Examples, and the exposed surface (adhesive surface) of the exposed adhesive layer was bonded to a glass plate (thickness: 1.2 mm). was used as the sample for measurement.

The evaluator used the same touch pen used in the friction measurement in Test Example 3 to perform a predetermined writing task on the surface of the writing quality improvement layer side (touch pen contact surface) of the above measurement sample. The writing quality was evaluated based on the following criteria. The results are shown in Table 3.
◎: Excellent writing quality was obtained.
○: Although it cannot be said to be an "excellent writing feeling," a good writing feeling within an acceptable range was obtained.
×: The writing quality was poor.

As is clear from Table 3, the writing quality improving sheets produced in the examples were able to satisfactorily reproduce the writing quality when written on paper with a writing instrument, and were able to achieve an excellent writing quality. Furthermore, the writing quality improving sheets produced in the examples obtained good results in evaluations based on various optical properties.

The writing quality improving sheet of the present invention is suitably used as the outermost layer of a touch panel on which a touch pen is used.

Claims (3)

A writing feeling improving sheet comprising a writing feeling improving layer and a base material provided on one side of the writing feeling improving layer, and having a touch pen contacting surface with which a touch pen comes into contact,
The surface of the writing quality improving layer opposite to the base material is the touch pen contact surface,
The writing quality improving layer is formed by curing a coating composition containing a curable component and fine particles,
The average particle size of the fine particles is 1 μm or more and 8 μm or less,
The content of the fine particles in the coating composition is 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the curable component,
After bringing the tip of a touch pen having an elastomer tip with a diameter of 0.5 mm into contact with the touch pen contact surface, a load of 200 g is applied to the touch pen, and the touch pen and the touch pen contact surface are brought into contact with each other. Regarding the dynamic friction coefficient measured when the touch pen is slid linearly at a predetermined sliding speed while maintaining the angle formed by the 45 degrees,
The coefficient of dynamic friction when the sliding speed is 1.5 mm/s is 0.13 or more and 0.35 or less,
The coefficient of dynamic friction when the sliding speed is 20 mm/s is 0.15 or more and 0.40 or less,
the dynamic friction coefficient when the sliding speed is 50 mm/s is 0.18 or more and 0.45 or less, and the dynamic friction coefficient when the sliding speed is 80 mm/s is 0.18 or more, A sheet for improving writing quality, characterized in that it is 0.47 or less. A writing feeling improving sheet comprising a writing feeling improving layer and a base material provided on one side of the writing feeling improving layer, and having a touch pen contacting surface with which a touch pen comes into contact,
The surface of the writing quality improving layer opposite to the base material is the touch pen contact surface,
The writing quality improving layer is formed by curing a coating composition containing a curable component and fine particles,
The average particle size of the fine particles is 1 μm or more and 8 μm or less,
The content of the fine particles in the coating composition is 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the curable component,
After bringing the tip of a touch pen having an elastomer tip with a diameter of 0.5 mm into contact with the touch pen contact surface, a load of 200 g is applied to the touch pen, and the touch pen and the touch pen contact surface are brought into contact with each other. Regarding the dynamic friction coefficient measured when the touch pen is slid linearly at a predetermined sliding speed while maintaining the angle formed by the 45 degrees,
When the measurement results are plotted on a coordinate plane with the sliding speed as the horizontal axis (unit: mm/sec) and the dynamic friction coefficient as the vertical axis,
The slope of the line segment connecting the coordinates where the sliding speed is 1.5 mm/sec and the coordinates where the sliding speed is 50 mm/sec is more than 0.0006 and less than 0.0072. A sheet to improve writing quality. A writing feeling improving sheet comprising a writing feeling improving layer and a base material provided on one side of the writing feeling improving layer, and having a touch pen contacting surface with which a touch pen comes into contact,
The surface of the writing quality improving layer opposite to the base material is the touch pen contact surface,
The writing quality improving layer is formed by curing a coating composition containing a curable component and fine particles,
The average particle size of the fine particles is 1 μm or more and 8 μm or less,
The content of the fine particles in the coating composition is 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the curable component,
After bringing the tip of a touch pen having an elastomer tip with a diameter of 0.5 mm into contact with the touch pen contact surface, a load of 200 g is applied to the touch pen, and the touch pen and the touch pen contact surface are brought into contact with each other. Regarding the dynamic friction coefficient measured when the touch pen is slid linearly at a predetermined sliding speed while maintaining the angle formed by the 45 degrees,
When the measurement results are plotted on a coordinate plane with the sliding speed as the horizontal axis (X-axis) (unit: mm/sec) and the dynamic friction coefficient as the vertical axis (Y-axis),
Coordinates where the sliding speed is 1.5 mm/s, coordinates where the sliding speed is 20 mm/s, coordinates where the sliding speed is 50 mm/s, and coordinates where the sliding speed is 80 mm/s. The approximate curve obtained by polynomial approximation for the coordinates of the four points is expressed by the following equations (1) to (4).
Y=aX ² +bX+c...(1)
-5×10 ^-5 ≦a≦-5×10 ^-6 ...(2)
0.0001≦b≦0.008…(3)
0.11≦c≦0.31…(4)
A writing quality improvement sheet that satisfies the following requirements.